Tìm x biết: a) |x + 3/4| = 1/2 b) |5/18 - x| - 7/24 = 0

* Hướng dẫn giải

a) $\left|x+\frac{3}{4}\right|=\frac{1}{2}\iff \left[\begin{array}{l}x+\frac{3}{4}=-\frac{1}{2}\\ x+\frac{3}{4}=\frac{1}{2}\end{array}\right.\iff \left[\begin{array}{l}x=-\frac{5}{4}\\ x=-\frac{1}{4}\end{array}\right.$

b) $\left|\frac{5}{18}-x\right|-\frac{7}{24}=0\iff \left|\frac{5}{18}-x\right|=\frac{7}{24}\iff \left[\begin{array}{l}\frac{5}{18}-x=-\frac{7}{24}\\ \frac{5}{18}-x=\frac{7}{24}\end{array}\right.\iff \left[\begin{array}{l}x=\frac{41}{72}\\ x=-\frac{1}{72}\end{array}\right.$